Link Aggregation described in IEEE 802.1AX-2008 (formerly IEEE 802.3ad), the contents of which are incorporated by reference, describes how to combine multiple Local Area Network (LAN) cables in parallel. The advantages of link aggregation in contrast with conventional connections using an individual cable include a higher potential transmission speed (e.g., 3 Gb/s versus a single Gigabit Ethernet (GbE)) and higher accessibility (i.e., protection and redundancy). Link aggregation allows for the distribution of Ethernet frames to all physical links available to a Link Aggregation Group (LAG) connection. Thus, the potential data throughput will exceed the data rate of a single physical link. The IEEE standard does not define a specific algorithm for distribution (Frame Distribution). However, individual guidelines are: the order of frames for a specific data communication packet may not be transposed, and frames may not be duplicated.
LAGs are typically deployed on faceplate ports, i.e., network facing ports. In a multi-card LAG, different faceplate ports are located on different line cards and internal to a switch, the different line cards communicate with one another over backplane ports. In a multi-switch LAG, different faceplate ports are located on different switches and the different switches communicate with one another over inter-switch connectivity ports. In either scenario or a combination of both, there are situations where packets egressing from a LAG are dropped due to congestion on the backplane ports or the inter-switch connectivity ports, which are not part of the LAG. Thus, it would be advantageous to have backplane port and inter-switch connectivity port congestion resiliency in a multi-card and/or multi-switch LAG.